1. Field of the Invention
The present invention relates to a sealing glass composition and a flat panel display apparatus using the same.
2. Background of the Related Art
A display device that has been widely used is a Cathode Ray Tube (CRT). The CRT, however, has problems in that the greater the display region, the heavier the weight and the greater the volume. Recently, however, a flat type display apparatus that solves the shortcomings of the CRT is part of a next-generation display industry, that is, undergoes continuous technological developments.
There has been active research, development and investment in next-generation display types such as Liquid Crystal Displays (LCD), Plasma Display Panels (PDP), Field Emission Devices (FED) and the like. In addition, an electro-chromic display using electrochemical properties, a Suspended Particle Display (SPD) using distributed particles, etc. have been researched as a prospective flat type display apparatus.
In a plasma display panel, a barrier rib is formed between a front panel and a rear panel forming one unit cell. Each cell is filled with a main discharge gas such as neon (Ne), helium (He) or a mixed gas (Ne+He) of Ne and He, and an inert gas containing a small amount of xenon. If the inert gas is discharged with a high frequency voltage, it generates vacuum ultraviolet rays. Phosphors formed between the barrier ribs are emitted to display images. A plasma display panel can be manufactured to be thin, and as such, this display type is among the leading next-generation display devices.
In a PDP display apparatus, the front panel and the rear panel are combined together by a sealing material such as frit glass with a predetermined distance therebetween. The conventional sealing material includes PbO—B2O3—ZnO as its main ingredient. When the sealing process is to occur, the PbO is heated up to a sealing temperature at which the sealing material is sufficiently softened to enable the sealing of the panel. If the softening temperature of the sealing material is too high, the plasma display panel can be damaged by the excessive heat. Therefore, the PbO is used to lower the melting point of the sealing material.
If the sealing material will be adhered to the panel, it should have a thermal expansion coefficient similar to that of the panel glass used in the PDP. Accordingly, B2O3 serves to lower thermal expansion coefficient of the sealing material and is used as a glass formation agent.
After the front panel and the rear panel are sealed, a discharge gas is injected. To prevent the leakage of the discharge gas from the sealing panels, the adhesion strength of the sealing material must be adhesive and such adhesion strength is increased through improvements of the chemical durability of the sealing material. A conventional sealing glass composition includes ZnO to improve chemical durability.
PbO, a major component of a conventional sealing material composition contains the Pb component that is very injurious to the human body. If the serious adverse health events may occur, the human body is exposed to Pb component while at work. In addition, if the Pb component is discarded, the Pb component will react to an acid or alkali component in underground water and will cause environmental problems due to contamination of solid and water.
Several potential alternative components such as Bi2O3—B2O3 and P2O5—SnO have low melting points and do not contain Pb. In the Bi2O3—B2O3 material, however, Bi2O3, a main ingredient, has a low melting point, but Bi itself is a heavy metal. There are problems in using Bi2O3—B2O3 given the possible adverse effects given the increased cost incurred because Bi is a rare material.
The P2O5—SnO material is environmentally-friendly, but the P2O5 component has a very low chemical durability that caused low mechanical strength. In addition, SnO is an expensive sub-component, and is difficult for vitrification if it added a lot.
Bi2O3 and P2O5, which are substitution materials for PbO, are combined with alkali metals in order to approximate the glass transition temperature of PbO. However, the need to use such alkali metals is problematic in that they reduce the lifespan of phosphors and/or the lifespan of the panel glass.